1. Field of the Invention
The present invention relates to an addition-curable silicone rubber composition and a cured product thereof, and relates particularly to a curable silicone rubber composition that produces a cured product with a superior refractive index, favorable rubber-like properties and strength characteristics, and almost no surface tackiness, as well as a cured product produced from such a composition.
2. Description of the Prior Art
Silicone rubber compositions exhibit excellent properties of weather resistance and heat resistance and the like, and form cured products with superior rubber-like properties such as hardness and elongation, and are consequently used in a wide variety of applications, but because they also exhibit surface tackiness, dust adhesion becomes a problem when such silicone rubber compositions are used as coating agents or the like for electrical and electronic components.
In the case of silicone varnishes that resolve this problem of surface tackiness, the occurrence of cracking becomes a problem. Furthermore, reduced hardness resins produced by adding a silicone oil to a silicone varnish are extremely brittle, and suffer from problems of reliability. A silicone rubber composition capable of forming a cured product with no surface tackiness and excellent crack resistance has been keenly sought for packages such as electrical and electronic components. Furthermore, in the case of optical components and optical semiconductors, increases in the refractive index are seen as a very desirable optical property.
In addition-curable silicone rubber compositions, the addition of a resin-like organopolysiloxane to improve the strength of the cured product is a commonly known technique. However, even in those cases where the strength of a cured product is raised by adding a resin-like organopolysiloxane, surface tackiness and dust adhesion remain problems.